Differences Between Japanese "Onsen" (Hot Springs) and "Sento" (Public Baths) and the Spring Quality/Form of Dogo Onsen

1. Definitions and Institutional Differences of "Onsen" and "Sento" in Japan

In Japan, places generally recognized as "facilities to take a bath" have different concepts in legal classification, namely "Onsen" and "Sento / Public Bath." The definitions and differences between the two, which are easily confused by travelers from abroad, are as follows.

Definition of Onsen: Based on Japan's "Hot Springs Act," this refers to hot water, mineral water, water vapor, etc., gushing from the ground that has a temperature of 25 degrees Celsius or higher at the time of gushing, or contains a specified amount of specified substances (any of the 19 items such as lithium ions or hydrogen ions) or more. This is a scientific and legal classification defined by the components of the hot spring source and geological conditions.

Definition of Sento: This term is used to refer to public baths used daily by local residents. While many facilities boil water to use, some public baths use natural hot spring water as it is.

In other words, "Onsen" is a definition of water quality and temperature, while "Sento" is a classification of the business style and purpose of use of the facility. Therefore, some Sentos use hot spring water, while others run tap water.

2. Historical Format of Dogo Onsen Maintained as a Public Bath

The three major soto-yu (public baths) of Dogo Onsen—"Dogo Onsen Honkan," "Dogo Onsen Bekkan Asuka-no-Yu," and "Tsubaki-no-Yu"—are city-owned public baths owned by Matsuyama City and operated by the designated administrator "Dogo Onsen Consortium."

Even the Dogo Onsen Honkan, which has historical architecture and luxurious decorations, maintains a framework under the system as a "public bath (sento-style operation)" that local residents and visitors can use at a public rate. Therefore, unlike the private uchi-yu (indoor baths) of high-class ryokans, it has the nature of a public place open to the local community.

The major feature of Dogo Onsen is that it allows visitors to bathe in real hot spring water with simple procedures similar to those of a Sento, despite being a historical hot spring resort.

3. Spring Quality Classification of Dogo Onsen and the Mechanism of Blended Water Distribution

The hot spring water used in Dogo Onsen is classified as an "alkaline simple hot spring" in scientific classification.

There are currently 18 hot spring sources in the Dogo area, and the temperatures of the pumped sources range from 20 to 55 degrees Celsius. In Dogo Onsen, the water obtained from these sources is collected at a central facility called the "bunyujo" (water distribution center), where hot spring waters of different temperatures are blended (mixed) at a fixed ratio.

By performing the blending process, the temperature of the water is adjusted to a suitable temperature of around 42 degrees Celsius for bathing as it is, without pressurizing/heating the water or diluting it by adding water (adding water). A supply system of "non-heated, non-diluted, free-flowing hot spring water direct from the source," which is rare even nationwide, is operated under the management of the entire region.

4. Respective Characteristics of Public Baths (Soto-yu) and Large Baths in Accommodation Facilities (Uchi-yu)

When bathing in a hot spring in the Dogo area, there are methods of using "public baths (soto-yu)" and using "hot spring ryokans and hotels (uchi-yu)."

・Characteristics of Public Baths (Soto-yu): The three bathhouses, Honkan, Asuka-no-Yu, and Tsubaki-no-Yu, correspond to this. They specialize in day-trip bathing, and are used for a short time by purchasing a bath ticket. Since the inclusion of towels varies depending on the course, you bring your own or purchase/rent one at the shop. It is a public place where local residents and travelers share the same space.

・Characteristics of Large Baths in Accommodation Facilities (Uchi-yu): In many ryokans and hotels in the Dogo area, the same Dogo Onsen water supplied from the distribution center is drawn. They are often operated exclusively for guests, and towels and amenities are abundantly provided in the changing rooms, allowing for a relaxing stay.

Since water is supplied to all facilities under common hot spring source management, they can be chosen according to your purpose and travel style.

5. Bathing Manners Inside the Bathhouse That Foreign Travelers Should Know

When using the public baths of Dogo Onsen, you are required to follow the official manners for sharing the space comfortably with other customers. The main items stipulated in the official manners (dogo.jp/manners) are as follows.

・Before Bathing: Avoid bathing while intoxicated. Taking photos/videos and operating smartphones in changing rooms and bathrooms are prohibited. Be sure to lock your changing locker, and move around with the key band with the key attached to your wrist.

・During Bathing: Before entering the bathtub, be sure to splash hot water over yourself (kake-yu) or wash your body first. Tie long hair with a rubber band or similar. Wearing swimsuits or bathing with a towel inside the bathtub is prohibited (do not put the towel in the bathtub; place it on your head or on the side). Do not swim or dive in the bathtub. Rinse the washbasins and stools you used with hot water and return them to their original places.

・After Bathing: Before returning to the changing room, wipe off moisture from the surface of your body with a tightly wrung towel near the bathroom exit.

Regarding tattoos, there is no clear provision of bathing restrictions written on the official website. However, as a matter of manners, bathing with towels or swimsuits is not permitted. At the Honkan shop, "bathing wear" that can be worn during bathing is sold for 500 yen (tax included). If you have any concerns, it is recommended to check with the local facility in advance.

6. Three Major Public Baths Composing the Dogo Area

The outlines of the three major public baths where you can experience the hot spring culture of Dogo Onsen are as follows.

1. Dogo Onsen Honkan: A historical building preserving Meiji period architecture. Multiple floors and courses are prepared, allowing for bathing and resting in a space designated as an Important Cultural Property (Kami-no-Yu downstairs: 6:00 - 23:00, etc.).

2. Dogo Onsen Bekkan Asuka-no-Yu: A bathhouse incorporating architectural styles of the Asuka period. In addition to the large baths, it features open-air baths, and special bathhouses and private rest rooms incorporating traditional crafts are set up on the second floor (1st floor bathroom: 6:00 - 23:00, etc.).

3. Tsubaki-no-Yu: Located near the center of Dogo Shopping Street, this is a bath for citizens rebuilt in 1984. It is widely popular among local residents as a simple public bath (6:30 - 23:00, rental towel 50 yen).

While each facility has a different history and background, they all supply the same non-heated and non-diluted hot spring water.

※ Business hours, fees, and operating schedules of each facility are subject to change. Please check the detail pages of each spot and official information for the latest details.